The number of atoms in $0.004 \ g$ of magnesium is:

Numbers of gram atoms of oxygen present in $0.8 \ mol$ of $C_4H_6O_6$ would be

Find the number of moles of sodium atoms in $6.9 \times 10^{-2} \ kg$ (Atomic mass $= 23 \ g \ mol^{-1}$)

The number of sodium atoms in $2 \ mol$ of sodium ferrocyanide $Na_4[Fe(CN)_6]$ is .......... $\times 10^{23}$. (Given $N_A = 6.022 \times 10^{23} \ mol^{-1}$)

If one atom of an element $X$ weighs $6.643 \times 10^{-23} \ g$,then find the number of moles of atoms in $50 \ kg$ of element $X$. (in $moles$)

Find the number of hydrogen atoms present in $6.0 \ g$ of urea $(NH_2CONH_2)$: